Information record medium with a record/reproduction area and a reproduction-dedicated area

ABSTRACT

On an information record medium ( 1 ), information is optically recorded and reproduced while a servo control is performed with respect to the information record medium by a push-pull method. The information record medium is provided with: a record/reproduction area (DA) having a groove track ( 2 ), which is wobbled and continuously formed and on which the information is recorded and reproduced by a phase changing method by use of a light beam (B) having a wavelength of not less than 630 nm (nanometer) and not more than 680 nm; and a reproduction-dedicated area (RA) where a plurality of phase pits (PI) are wobbled and formed in advance, each having a depth of not less than 60 nm and not more than 90 nm and where only an information reproduction is possible by the light beam.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to an information recordmedium, and more particularly to an information record medium on whichinformation can be optically recorded and reproduced in accompanimentwith a tracking servo control of a so-called push-pull method.

[0003] 2. Description of the Related Art

[0004] There is a DVD as an information record medium, whose recordcapacity is improved to be as high as several times of that of aconventional CD (Compact Disc), and on which video information and audioinformation in an information amount of one full move or the like can berecorded.

[0005] Other than the DVD dedicated for reproduction such as a DVD-ROM(DVD-Read Only), there is a so-called DVD-RW (DVD Re-recordable) as aDVD standard, on which the information can be reproduced and recorded ata plurality of times, and on which the information can be reproduced byan information reproducing apparatus for reproducing the DVD dedicatedfor reproduction.

[0006] Here, on an information record medium based on the DVD-RWstandard, there is formed a groove track, which has a width of about 0.3μm and a depth of about 20 nm (nanometer) and which is wobbled at aconstant frequency, as an information track on which the opticalinformation recording and reproduction is performed. At this time, thereason why the groove track is wobbled is to generate a record standardclock signal having an accurate frequency synchronous with the rotationof the DVD-RW, by detecting the frequency of the wobbling at the time ofinformation recording.

[0007] On the other hand, the DVD-RW basically has a record capacitysubstantially same as that of the DVD dedicated for reproduction. Thus,the video information etc., recorded on the DVD dedicated forreproduction may be illegally copied onto the DVD-RW. At this time, thevideo information or the like recorded on the DVD dedicated forreproduction is generally protected by a copy right, so that the copyright holder drastically suffers losses if the above mentioned illegalcopy is often performed.

[0008] Therefore, there is a countermeasure against such an illegal copyaccording to the DVD-RW standard that the area on the DVD-RW, whichcorresponds to the area where control information for controlling thereproduction is recorded on the DVD dedicated for reproduction, is setas an area where recording is impossible on the DVD-RW, to therebyprevent the illegal copy.

[0009] In addition to this, according to the DVD-RW standard, it ispermitted to prepare an area dedicated for reproduction on the abovementioned area where recording is impossible, and to record thepredetermined reproduction control information etc., in advance in thisarea. Further, according to the DVD-RW standard, the phase pit, which isused in the DVD dedicated for reproduction, is also used to record thispredetermined reproduction control information etc., in the areadedicated for reproduction of the DVD-RW.

[0010] On the other hand, according to the DVD-RW standard, at the timeof optically recording and/or reproducing the information by use of thelight beam such as a laser light with respect to the DVD-RW, thetracking servo control is performed by means of the so-called push-pullmethod.

[0011] However, if it is attempted to obtain the tracking error signalby the push-pull method at the time of reproducing the reproductioncontrol information, which is recorded in the area dedicated forreproduction by forming the phase pit, it may be difficult to obtain thetracking error signal and a detection signal corresponding to thereproduction control information at an adequate signal quality, becauseof an influence of an interference with a pre-pit formed in the areadedicated for reproduction in advance (i.e., a pre-pit, which is formedwithin a land track formed adjacent to the groove track and is to recordaddress information (i.e., address information indicating a recordposition on the DVD-RW) which is used when recording the informationonto the groove track other than the area dedicated for reproduction),which is a problem.

SUMMARY OF THE INVENTION

[0012] It is therefore an object of the present invention to provide aninformation record medium, on which the detection signal correspondingto the reproduction control information and the tracking error signal bymeans of the push-pull method can be obtained at adequate signalqualities, in case that the reproduction control information isreproduced from the area dedicated for reproduction on the DVD-RW.

[0013] The above object of the present invention can be achieved by aninformation record medium, on which information is optically recordedand reproduced while a servo control is performed with respect to theinformation record medium by a push-pull method. The information recordmedium is provided with: a record/reproduction area having a groovetrack, which is wobbled and continuously formed and on which theinformation is recorded and reproduced by a phase changing method by useof a light beam having a wavelength of not less than 630 nm (nanometer)and not more than 680 nm; and a reproduction-dedicated area where aplurality of phase pits are wobbled and formed in advance, each having adepth of not less than 60 nm and not more than 90 nm and where only aninformation reproduction is possible by the light beam.

[0014] According to the information record medium of the presentinvention, since the phase pit formed in the reproduction-dedicated areahas the depth of not less than 60 nm and not more than 90 nm, it ispossible to obtain both of (i) a detection signal corresponding to theinformation to be reproduced by an enough output level by the light beamfor recording and reproducing having the wavelength in the abovementioned range and (ii) an error signal for a servo control of thepush-pull method, in the reproduction-dedicated area.

[0015] In this manner, it is possible to prevent an illegal copy withrespect to the information record medium and an illegal reproduction ofthe illegally copied information, by preparing thereproduction-dedicated area where only the reproduction is possible, andit is also possible to record the necessary information in advance suchas the copy control information or the like by using the phase pitwithin the reproduction-dedicated area and then appropriately reproducethe necessary information.

[0016] In one aspect of the information record medium of the presentinvention, the depth of the phase pit is not less than 70 nm and notmore than 80 nm.

[0017] According to this aspect, since the depth of the phase pit formedin the reproduction-dedicated area is not less than 70 nm and not morethan 80 nm, it is possible to obtain the detection signal and the errorsignal at the higher output levels.

[0018] In another aspect of the information record medium of the presentinvention, a pre-pit indicating address information, which correspondsto a record position on the information record medium, of theinformation, is formed within at least the record/reproduction areaexcept the reproduction-dedicated area.

[0019] According to this aspect, it is possible to prevent the operationof obtaining the detection signal and the error signal from thereproduction-dedicated area from being disturbed by the pre-pit.

[0020] In another aspect of the information record medium of the presentinvention, unreadable area, which has a plurality of phase pits wobbledand formed in advance and where it is not possible to record orreproduce the information by the light beam, is further formed betweenthe reproduction-dedicated area and the record/reproduction area on theinformation record medium.

[0021] According to this aspect, since the unreadable area is formedbetween the reproduction-dedicated area and the record/reproductionarea, it is possible to avoid an illegal copy and an illegalreproduction with respect to the information record medium, by theexistences of the unreadable area and the reproduction-dedicated area.

[0022] In this aspect, a pre-pit may be formed within the unreadablearea, and the address information indicated by the pre-pit within theunreadable area, may be set on the basis of the address informationcorresponding to a head of the record/reproduction area within theinformation record medium.

[0023] By constructing in this manner, it is possible to record theinformation with respect to the record/reproduction area while graspingthe record position accurately without being influenced by the existenceof the reproduction-dedicated area.

[0024] The nature, utility, and further features of this invention willbe more clearly apparent from the following detailed description withrespect to preferred embodiments of the invention when read inconjunction with the accompanying drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a plan view of a DVD-RW as an embodiment of the presentinvention;

[0026]FIG. 2A is a perspective view of the DVD-RW at a portion where apre-pit is formed of the embodiment;

[0027]FIG. 2B is a partial sectional view of the DVD-RW in theembodiment;

[0028]FIG. 3 is an enlarged plan view of the DVD-RW at an area dedicatedfor reproduction and an unreadable area in the present embodiment;

[0029]FIG. 4A is a partial sectional view of the DVD-RW at a portionwhere the phase pit is formed in the area dedicated for reproduction inthe embodiment;

[0030]FIG. 4B is a partial sectional view of the DVD-RW at a portionwhere the phase pit is not formed in the area dedicated for reproductionin the embodiment;

[0031]FIG. 5 is a diagram showing one portion of a record format in theDVD-RW in the embodiment; and

[0032]FIG. 6 is a graph showing a result of an experiment correspondingto the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] An embodiment of the present invention will be now explained withreference to FIG. 1 to FIG. 5. In the embodiment explained hereinbelow,the present invention is applied to the DVD-RW as one example of aninformation record medium, which is a DVD capable of rerecording theinformation at a plurality of times.

[0034]FIG. 1 is a plan view of the DVD-RW as the embodiment (i.e., aplan view at the time of shipment from a manufacturing factory (which issimply referred to as “at the shipment” hereinafter)). FIG. 2A and FIG.2B are the perspective and sectional views of the DVD-RW in which apre-pit described layer is formed. FIG. 3 shows the structures of thearea dedicated for reproduction and the unreadable area described later.FIG. 4 shows the structure of the area dedicated for reproduction. FIG.5 shows one portion of the format of the DVD-RW. FIG. 6 indicates aresult of the experiment of the present embodiment.

[0035] As shown in FIG. 1, at the shipment, a DVD-RW 1 as the embodimentof the present invention has such a structure that a clamp hole CH isopened at a center thereof, which is used to fix the DVD-RW 1 onto aspindle motor (for rotating the DVD-RW 1 at a rotation number set inadvance) of an information recording apparatus (not illustrated) forrecording record information (which is defined as information such asvideo information, audio information or the like other thanpre-information described later to be primarily recorded on the DVD-RW1, hereinafter) onto the DVD-RW 1, and that a reproduction-dedicatedarea RA, which is an area dedicated for reproduction where theinformation can be only reproduced, and an unreadable area UA where theinformation cannot be reproduced or recorded, are prepared in a coaxialor spiral manner.

[0036] At this time, an area on the DVD-RW 1, which corresponds to anarea where the control information for controlling the reproduction isrecorded in case of the DVD dedicated for reproduction, is assigned tothe reproduction-dedicated area RA and the unreadable area UA, so as toprevent the illegal copy with respect to the DVD-RW 1 as describedabove.

[0037] After the initialization set in advance is performed at firstupon recording the record information onto the DVD-RW 1 by theinformation recording apparatus, the DVD-RW 1 is provided with: (i) acontrol information area RI where control information used for recordingand reproducing the record information on the DVD-RW 1 is recorded bythe initialization (e.g., setting information to set a light intensityof the light beam to perform recording and reproducing, record controlinformation used for recording or the like); (ii) a lead in area LIwhere start information to start recording and reproducing is recordedby the initialization; and (iii) a record/reproduction area DA where therecord information to be primarily recorded on the DVD-RW 1 is actuallyrecorded, in this order from an inner circumference side thereof asindicated by broken lines in FIG. 1. Incidentally, in FIG. 1, in orderto distinguish the reproduction-dedicated area RA and the unreadablearea UA which have been already formed at the shipment, from the controlinformation area RI, the lead in area LI and the record/reproductionarea DA which are formed after the initialization, the division lines ofthe control information area RI, the lead in area LI and therecord/reproduction area DA are illustrated as the broken lines.

[0038] At this time, after the initialization, thereproduction-dedicated area RA and the unreadable area UA are bothincluded in the lead in area LI.

[0039] Further, a lead out area (not illustrated), where end informationindicating an end of recording the record information with respect tothe DVD-RW 1 is recorded, is formed at the outermost circumference ofthe record/reproduction area DA when the operation of recording therecord information with respect to the DVD-RW 1 as a whole is ended.

[0040] Next, the structure of the DVD-RW 1 at the record/reproductionarea DA is explained with reference to FIG. 2. FIG. 2A is a perspectiveview showing the structure of the DVD-RW 1 at the record/reproductionarea DA, while FIG. 2B is a sectional view seeing a groove track in FIG.2A from an arrow direction in FIG. 2A.

[0041] In the DVD-RW 1, address information indicating the recordposition of the information on the DVD-RW 1 is recorded aspre-information at the shipment by forming a pre-pit (which may bereferred to as a “land pre-pit”), in an area which is to become theabove mentioned lead in area LI after the initialization by theinformation recording apparatus (except for the reproduction-dedicatedarea RA described later) and the record/reproduction area DA.

[0042] In addition, in the area which is to become therecord/reproduction area DA after the initialization, a low frequencysignal, which is the standard to generate a record clock signal used forcontrolling a recording operation on the whole with respect to theDVD-RW 1 (including the rotation number control of the DVD-RW 1) in theinformation recording apparatus, is also recorded in advance at theshipment, by wobbling a groove track 2 described later at the lowfrequency (i.e., by wobbling the groove track 2 by a cycle correspondingto the low frequency).

[0043] Next, the structure is more tangibly explained.

[0044] In FIG. 2A and FIG. 2B, the DVD-RW 1 is a phase changing typeDVD-RW, which has a record layer 11 comprising a phase changing thinfilm and on which the record information can be recorded at a pluralityof times. The groove track 2, which is the information track on whichthe record information is to be recorded, and a land tack 3, which is toguide a light beam B such as a laser beam as a reproduction light or arecording light onto the groove track 2, are formed adjacent to eachother on a disc substrate 9.

[0045] In the respective groove track 2, especially as shown in FIG. 2B,(i) protection layers 5 and 8, which sandwich the record layer 11 andhave a function to protect the record layer 11, (ii) a reflection layer6 to reflect the light beam B at the time of reproducing the recordedrecord information and (iii) a resin layer 9A and a protection layer 7to further protect the record layer 11, the protection layers 5 and 8and the reflection layer 6 from an external atmosphere or the like, arelaminated and formed on the substrate 9.

[0046] At this time, it is standardized that the depth of the groovetrack 2 is not less than 20 nm (nanometer) and not more than 35 nm atthe position of the record layer 11. The interval between central linesof adjacent turns of the groove track 2 is 0.74 μm.

[0047] On the other hand, a pre-pit 4 corresponding to the abovementioned pre-information is already formed on the land track 3 at theshipment.

[0048] Further, in the DVD-RW 1, the groove track 2 is wobbled to be incorrespondence with the low frequency signal (e.g., a 140 kHz signal)which is used to generate the above mentioned record clock signal.

[0049] At the time of recording the record information onto the DVD-RW1, as the information recording apparatus detects the low frequencysignal at the wobbling of the groove track 2, the record clock signal isobtained, so that the recording operation on the whole with respect tothe DVD-RW 1 is controlled on the basis of the obtained record clocksignal. Along with this, as the information recording apparatus obtainsthe pre-information in advance by detecting the pre-pit 4, the optimumoutput of the light beam B as the recording light or the like is set onthe basis of the obtained pre-information, so that the recordinformation is recorded at the record position on the basis of thisobtained address information.

[0050] As shown in FIG. 2A, at the time of recording the recordinformation, the record information is recorded by irradiating the lightbeam B such that the center of the light beam B is positioned at thecenter of the groove track 2, and then forming the phase change pitcorresponding to the record information on the groove track 2.

[0051] Here, the size of a light spot SP is set such that one portion ofthe light spot SP is on the land track 3 beside the groove track 2.Then, by using the reflection light of this one portion of the lightspot SP irradiated on the land track 3, the pre-information is detectedfrom the pre-pit 4 by the push-pull method (e.g., the radial push-pullmethod using a photo-detector divided by a division line parallel to therotation direction of the DVD-RW 1), so that the pre-information can beobtained. Further, the multiplexed frequency signal is detected from thegroove track 2 by using the reflection light of the light spot SPirradiated on the groove track 2, so that the record clock signal isgenerated or the address information is obtained.

[0052] Further, it is also standardized that a so-called tracking servocontrol to accurately irradiate the light beam B onto the groove 2 in amanner shown in FIG. 1A by controlling the light beam B to track thepositional change of the groove track 2 (i.e., the positional change inthe radial direction in accompaniment with the rotation of the DVD-RW1), is performed by means of the push-pull method.

[0053] Next, the structure of the DVD-RW 1 in the reproduction-dedicatedarea RA is explained with reference to FIG. 3, FIG. 4A and FIG. 4B. FIG.3 is an enlarged plan view showing the structure in the vicinity of theboundary between the reproduction-dedicated area RA and the unreadablearea UA of the DVD-RW 1. FIG. 4A is a partial sectional view showing theportion where the phase pit is formed in the reproduction-dedicated areaRA (i.e., the A-A′ sectional view of FIG. 3) which is seen from the samedirection as FIG. 2B. FIG. 4B is a partial sectional view showing theportion where the phase pit is not formed in the reproduction-dedicatedarea RA (i.e., the B-B′ sectional view of FIG. 3) which is seen from thesame direction as FIG. 2B.

[0054] The groove track 2 and the land track 3 continuing as shown inFIG. 2A and FIG. 2B are not formed in the above mentionedreproduction-dedicated area RA.

[0055] In the reproduction-dedicated area RA, the reproduction controlinformation or the like used to reproduce the record information fromthe DVD-RW 1 is recorded by a phase pit PI (i.e., a phase pit, which issame as the phase pit formed on the DVD dedicated for reproduction andwhich is to judge the presence or absence of the phase pit and therebydetect the reproduction control information or the like, as the lightbeam B irradiated on the area where the phase pit is formed isdiffracted by the phase pit), which is intermittently formed and iswobbled at the same frequency as the groove track 2 as shown in FIG. 3(in which the condition of wobbling is illustrated by a central lineCL).

[0056] At this time, the depth of the phase pit PI within thereproduction-dedicated area RA is not less than 60 nm (nanometer) andnot more than 90 nm (preferably not less than 70 nm and not more than 80nm) at the position of the record layer 11. The interval between thecentral lines of one phase pit PI and another phase pit PI which areadjacent to each other in the radial direction of the DVD-RW 1 is set to0.74 a m same as the case of the groove track 2.

[0057] On the other hand, the portion of the reproduction-dedicated areaRA where the phase pit PI is not formed is a plane surface as shown inFIG. 4B.

[0058] In the reproduction-dedicated area RA, the pre-pit 4 is notformed. This is because, if the phase pit PI and the pre-pit 4 areformed within the same area, it is difficult or impossible to detectboth of those pits since both of those pits are optically interferingwith each other.

[0059] Next, the structure of the DVD-RW 1 at the unreadable area UA isexplained with reference to FIG. 3.

[0060] In the above described unreadable area UA, there is not formedthe groove track 2 or the land track 3 continuing in the same manner asthe reproduction-dedicated area RA.

[0061] In the unreadable area UA, the phase pit PI′ is wobbling and isirregularly formed.

[0062] At this time, the depth of the phase pit PI′ is not less than 20nm and not more than 35 nm at the position of the record layer 11 (i.e.,the same depth as the depth of the groove track 2). By this, it isconstructed such that, even if the phase changing pit is formed by thelight beam B in the record layer 11 within the unreadable area UA, thecontent of the phase changing pit cannot be detected by the interferencebetween the phase changing pit and the phase pit PI′ formed on the upperportion of the phase changing pit.

[0063] In the unreadable area UA, the address information is recorded bythe pre-pit 4. Thus, at the time of recording the record information,the record position on the DVD-RW 1 can be grasped by the informationrecording apparatus before the light beam B for recording reaches therecord/reproduction area DA in accompaniment with the rotation of theDVD-RW 1.

[0064] The above described phase pits PI and PI′ may be collectivelycalled as “emboss pre-pits” as the occasion demands.

[0065] Next, the record format of the DVD-RW 1 after the lead in area LIand the record/reproduction area DA are formed on the DVD-RW 1 isexplained with reference to FIG. 5.

[0066] As shown in FIG. 5, after the initialization, in the lead in areaLI, there are an initial zone IZ where all zero data (“00h”) arerecorded, a reference code zone RZ where the reference code includingthe start information or the like is recorded, a first buffer zone B1where all zero data are recorded, the above mentionedreproduction-dedicated area RA and the unreadable area UA, and a secondbuffer zone B2 where all zero data are recorded, in this order from theinner circumference side of the DVD-RW 1.

[0067] Among those, the pre-pit 4 is formed in all the lead in area LIexcept the reproduction-dedicated area RA. The address informationindicated by the pre-pit 4 is set to increment sequentially (i.e.,increase in digital) from the inner circumference side in the initialzone IZ, the reference code zone RZ and the first buffer zone B1 fromthe inner circumference side as shown in the left portion of FIG. 5. Onthe other hand, the address information indicated by the pre-pit 4 isset to decrement (i.e., decrease in digital), as sequentiallyreverse-calculated from the most inner circumference portion of therecord/reproduction area DA (i.e., the most outer circumference portionof the second buffer zone B2) in the unreadable area UA and the secondbuffer zone B2. Therefore, the address information is discontinuousbetween the most inner circumference portion and the most outercircumference portion of the reproduction-dedicated area RA.

[0068] On the other hand, a so-called sector number of the recordinformation, which corresponds to the address information, is recordedby the phase pit PI in advance at the shipment in thereproduction-dedicated area RA, as shown in the right portion of FIG. 5.The sector number is recorded in the lead in area except thereproduction-dedicated area RA and the unreadable area UA, such that thesector number is continuous including the sector number recorded in thereproduction-dedicated area RA after the initialization. At this time,in the unreadable area UA, the sector number changes continuouslybetween the most inner circumference portion and the most outercircumference portion of the unreadable area UA.

[0069] Next, the reason why the depth of the phase pit PI in thereproduction-dedicated area RA is set to be not less than 60 nm and notmore than 90 nm (preferably not less than 70 nm and not more than 80 nm)which is deeper than the groove track 2 is explained with reference toFIG. 6.

[0070]FIG. 6 shows a graph indicating the relationship between (i) theoutput level of the detection signal detected from thereproduction-dedicated area RA (i.e., the detection signal correspondingto the sector number etc., recorded by the phase pit PI) and the outputlevel of the tracking error signal for the tracking servo control bymeans of the push-pull method and (ii) the depth of the phase pit PI.FIG. 6 shows the result of the experiment in such a case that thewavelength of the light beam B is not less than 630 nm and not more than680 nm.

[0071] As described above, in order to detect the sector informationetc., recorded in advance in the reproduction-dedicated area RA whileperforming the tracking servo control accurately in thereproduction-dedicated area RA, it is necessary that both of the abovementioned detection signal and the tracking error signal are detected atthe appropriate output levels. As shown in FIG. 6, if the depth of thephase pit PI is not less than 60 nm and not more than 90 nm (as in arange B in FIG. 6), both of those signals can be detected at thetolerable output levels. In addition, it is possible to detect both ofthose signals at the most appropriate levels if the depth of the phasepit PI is not less than 70 nm and not more than 80 nm (as in a range Ain FIG. 6).

[0072] Therefore, the phase pit PI in the present embodiment isconstructed such that the depth of the phase pit PI is not less than 60nm and not more than 90 nm (preferably not less than 70 nm and not morethan 80 nm).

[0073] As described above, according to the DVD-RW 1 of the embodiment,since the phase pit PI formed in the reproduction-dedicated area RA hasthe depth of not less than 60 nm and not more than 90 nm, it is possibleto obtain the detection signal and the tracking error signal at theenough output levels by the light beam B having the wavelength range ofnot less than 630 nm and not more than 680 nm.

[0074] Further, it is possible to obtain the detection signal and thetracking error signal at the higher output level, if the depth of thephase pit PI formed in the reproduction-dedicated area RA is not lessthan 70 nm and not more than 80 nm.

[0075] It is also possible to prevent the operation of obtaining thetracking error signal and the detection signal from thereproduction-dedicated area RA from being disturbed by the pre-pit 4since the pre-pit 4 is formed within at least the record/reproductionarea DA except the reproduction-dedicated area RA.

[0076] Further, it is possible to surely avoid the illegal copy and theillegal reproduction with respect to the DVD-RW 1 by the existence ofthe unreadable area UA and the reproduction-dedicated area RA since theunreadable area UA is formed between the reproduction-dedicated area RAand the record/reproduction area DA.

[0077] Furthermore, since the pre-pit 4 is formed within the unreadablearea UA and since the address information indicated by the pre-pit 4within the unreadable area UA is set as reverse-calculated from theaddress information corresponding to the most inner circumferenceportion of the record/reproduction area DA, it is possible to record theinformation with respect to the record/reproduction area DA whilegrasping the record position accurately while it is not influenced bythe existence of the reproduction-dedicated area RA.

[0078] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

[0079] The entire disclosure of Japanese Patent Application No.2000-39800 filed on Feb. 14, 2000 including the specification, claims,drawings and summary is incorporated herein by reference in itsentirety.

What is claimed is:
 1. An information record medium, comprising: alead-in area; a reproduction-dedicated area in which control data ispre-recorded first phase pits; and a record area in which a groove isformed and in which information is capable of being recorded, whereinthe groove has a first depth, and the phase pits have a second depthwhich is greater than the first depth.
 2. The medium according to claim1, wherein the reproduction-dedicated area is within the lead-in area.3. The medium according to claim 1, wherein the first depth is not lessthan 20 nm and not more than 35 nm.
 4. The medium according to claim 1,wherein the second depth is not less than 60 nm and not more than 90 nm.5. The medium according to claim 3, wherein the second depth is not lessthan 60 nm and not more than 90 nm.
 6. The medium according to claim 1,wherein the groove is wobbled at a predetermined frequency.
 7. Themedium according to claim 1, wherein the first phase pits are wobbled ata predetermined frequency.
 8. The medium according to claim 6, whereinthe groove is wobbled at the same frequency as the frequency at whichthe phase pits are wobbled.
 9. The medium according to claim 1, whereinthe lead-in area comprises an unreadable area in which second phase pitshaving the second depth are recorded.
 10. The medium according to claim1, wherein the record area comprises pre-pits having address informationindicating a recording position on the information record medium. 11.The medium according to claim 9, wherein the unreadable area comprisespre-pits having address information indicating a recording position onthe information record medium.
 12. The medium according to claim 10,wherein the reproduction-dedicated area has no pre-pits having addressinformation.
 13. The medium according to claim 9, wherein the secondphase pits are wobbled at a predetermined frequency.
 14. The mediumaccording to claim 9, wherein the second phase pits in the unreadablearea are formed irregularly.